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Effect of adrenergic stimulation on Rb + uptake in normal and ischemic areas of isolated pig hearts: 87 Rb MRI study
Author(s) -
Kupriyanov V.V.,
Xiang B.,
Sun J.,
Jilkina O.
Publication year - 2002
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.10187
Subject(s) - dobutamine , propranolol , perfusion , stimulation , chemistry , medicine , heart rate , cardiology , endocrinology , anesthesia , hemodynamics , blood pressure
The role of adrenergic stimulation in Rb + uptake in normal and ischemic areas of pig hearts was investigated using an agonist (dobutamine) and an antagonist (S‐propranolol). The left anterior descending artery (LAD) in isolated pig hearts was cannulated to maintain adequate perfusion of the LAD bed (2.2–2.8 ml/min/g). Rb + loading was initiated by switching perfusion to Rb + ‐containing Krebs‐Henseleit (KH) buffer in the presence of 0.1 μM dobutamine, 0.5 μM propranolol, or no drug (control), and the LAD flow was reduced to 10% of the baseline for 120 min. The flow through the LAD was then restored to normal and the drugs were removed. In all groups the rate of Rb + uptake obtained from serial 87 Rb images was severely depressed in the ischemic anterior wall relative to that in the normal posterior wall. Dobutamine increased the rate of Rb + uptake in the posterior wall (6.3% ± 1.4% vs. 2.5% ± 0.25% per minute in control) and did not affect the rate in the anterior wall (0.86% ± 0.40% vs. 1.14% ± 0.19% per minute in control). Propranolol did not affect Rb + uptake in either of these areas. We conclude that the stimulation of Rb + uptake by dobutamine is related to activation of Na + /K + ATPase and passive Na + influx in normal tissue. The lack of any effect of propranolol implies a low level of endogenous norepinephrine during low‐flow (LF) ischemia. Magn Reson Med 48:15–20, 2002. © 2002 Wiley‐Liss, Inc.